Hilary Duff was born in Houston, Texas, the second child of Bob Erhard Duff, owner of a chain of convenience stores, and Susan Colleen Cobb, a homemaker. After Duff's mother encouraged her to take an acting class alongside her older sister, Haylie Katherine Duff, both girls won parts in various local theatre productions. At the age of six, the Duff sisters participated in the ballet The Nutcracker Suite with Columbus Ballet Met in San Antonio. The siblings became more enthusiastic about the idea of acting professionally, and eventually relocated to California with their mother. Bob Erhard Duff stayed at the family home in Houston to maintain their business. After several years of auditions and meetings, the Duff sisters were cast in several television commercials.